Welcome to the North American Subaru Impreza Owners Club Tuesday October 27, 2020
Home Forums Images WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Go Back   NASIOC > NASIOC Technical > Built Motor Discussion

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.







* As an Amazon Associate I earn from qualifying purchases. 
* Registered users of the site do not see these ads. 
Reply
 
Thread Tools Display Modes
Old 09-11-2020, 12:51 PM   #1
WRXXXED
Scooby Specialist
 
Member#: 432652
Join Date: Oct 2015
Location: Gap, PA
Vehicle:
2010 Subaru WRX STI
61K (Gray)

Default Carbon filled pistons, white tipped spark plugs, and white on valves

So im tearing my ej257 down and this just astounds me. What is causing all this? They are manley pistons, i suspected bad HGs (which explains the white on the valves and spark plugs) but why is there so much carbon on the piston face? It looks like a mix of coolant and oil but i cant be certain... any thoughts?
* Registered users of the site do not see these ads.
WRXXXED is offline   Reply With Quote
Sponsored Links
* Registered users of the site do not see these ads.
Old 09-11-2020, 12:53 PM   #2
WRXXXED
Scooby Specialist
 
Member#: 432652
Join Date: Oct 2015
Location: Gap, PA
Vehicle:
2010 Subaru WRX STI
61K (Gray)

Default

Quote:
Originally Posted by WRXXXED View Post
So im tearing my ej257 down and this just astounds me. What is causing all this? They are manley pistons, i suspected bad HGs (which explains the white on the valves and spark plugs) but why is there so much carbon on the piston face? It looks like a mix of coolant and oil but i cant be certain... any thoughts?
Pictures:
https://drive.google.com/folderview?...4cAFUvl1qIO9mW
WRXXXED is offline   Reply With Quote
Old 09-11-2020, 01:53 PM   #3
BlackFighter
Scooby Specialist
 
Member#: 193940
Join Date: Nov 2008
Location: Philly
Vehicle:
2004 WRX STI Black
RalliSpec Shortblock

Default

link requires a sign in
BlackFighter is online now   Reply With Quote
Old 09-11-2020, 02:01 PM   #4
rtv900
Scooby Guru
 
Member#: 428511
Join Date: Aug 2015
Location: philadelphia
Vehicle:
2016 STI

Default

white on valves and spark plugs just means a relatively lean burn, maybe even a perfect one depending what you really mean by "white"

nothing to do with coolant
and every piston has a carbon coating once it's run, so again, depends what you really mean and how much
pics don't work so nobody knows
rtv900 is online now   Reply With Quote
Old 09-11-2020, 02:40 PM   #5
WRXXXED
Scooby Specialist
 
Member#: 432652
Join Date: Oct 2015
Location: Gap, PA
Vehicle:
2010 Subaru WRX STI
61K (Gray)

Default

Quote:
Originally Posted by rtv900 View Post
white on valves and spark plugs just means a relatively lean burn, maybe even a perfect one depending what you really mean by "white"

nothing to do with coolant
and every piston has a carbon coating once it's run, so again, depends what you really mean and how much
pics don't work so nobody knows
For some reason it says im not allowed to post pictures, hopefully this works:

https://ibb.co/Y8svbyS
https://ibb.co/N2Lz0Fr
https://ibb.co/f1txMMC
https://ibb.co/j40NfwF
WRXXXED is offline   Reply With Quote
Old 09-11-2020, 02:42 PM   #6
WRXXXED
Scooby Specialist
 
Member#: 432652
Join Date: Oct 2015
Location: Gap, PA
Vehicle:
2010 Subaru WRX STI
61K (Gray)

Default

Quote:
Originally Posted by BlackFighter View Post
link requires a sign in
Replied with links that hopefully work
WRXXXED is offline   Reply With Quote
Old 09-11-2020, 02:52 PM   #7
rtv900
Scooby Guru
 
Member#: 428511
Join Date: Aug 2015
Location: philadelphia
Vehicle:
2016 STI

Default

wow that is a lot of crap on those pistons
personally I don't think the exhaust valves and plugs look so bad, the difference however between them and the rest of the chamber is what seems odd to me.
The rest of the cylinder looks like a crappy rich poor mixed burn, but the exhaust and plug look like a very stoich or borderline lean high egt situation.
Was it running poorly or what?
rtv900 is online now   Reply With Quote
Old 09-11-2020, 03:06 PM   #8
WRXXXED
Scooby Specialist
 
Member#: 432652
Join Date: Oct 2015
Location: Gap, PA
Vehicle:
2010 Subaru WRX STI
61K (Gray)

Default

Quote:
Originally Posted by rtv900 View Post
wow that is a lot of crap on those pistons
personally I don't think the exhaust valves and plugs look so bad, the difference however between them and the rest of the chamber is what seems odd to me.
The rest of the cylinder looks like a crappy rich poor mixed burn, but the exhaust and plug look like a very stoich or borderline lean high egt situation.
Was it running poorly or what?
Yeah it is really gunked up. Well one day i was wot and it bogged/lurched around 15lbs and showed-2.40 knock but the usual is 23lbs of boost. So i kept out of it and the next day before start up i took the rad cap off of the upper coolant reservoir and started it. It looked like it was boiling so i knew it was a HG issue.

I guess the difference could be a blowby issue but the boiling coolant is what made me think it was a HG issue

So i bought a cracked ringland block and planned a new short block build. Took this one out of the car and started trearing it down and was suprised at how much crap it had in the cylinders.

Im planning on moving the heads off this tore down engine to the new shortblock so is it necessary for the heads to be disassembled and cleaned or should i just use a degreaser and clean the carbon from the chamber the best i can?
WRXXXED is offline   Reply With Quote
Old 09-11-2020, 03:17 PM   #9
subaru_gc8
Scooby Specialist
 
Member#: 29292
Join Date: Nov 2002
Chapter/Region: SCIC
Location: Orange County CA
Vehicle:
2004 WRX wagon
silver

Default

it looks like alot of carbon building up, di you run it very hard?
subaru_gc8 is offline   Reply With Quote
Old 09-11-2020, 03:38 PM   #10
WRXXXED
Scooby Specialist
 
Member#: 432652
Join Date: Oct 2015
Location: Gap, PA
Vehicle:
2010 Subaru WRX STI
61K (Gray)

Default

Quote:
Originally Posted by subaru_gc8 View Post
it looks like alot of carbon building up, di you run it very hard?
Not too hard i would say, its a rotated 3582r daily driver, i did one track day with it where oil temps saw 240+ degrees but before and after that never saw above 220, do oil changes every 3k miles etc, the basic maintenance stuff
WRXXXED is offline   Reply With Quote
Old 09-11-2020, 03:43 PM   #11
subaru_gc8
Scooby Specialist
 
Member#: 29292
Join Date: Nov 2002
Chapter/Region: SCIC
Location: Orange County CA
Vehicle:
2004 WRX wagon
silver

Default

Quote:
Originally Posted by WRXXXED View Post
Not too hard i would say, its a rotated 3582r daily driver, i did one track day with it where oil temps saw 240+ degrees but before and after that never saw above 220, do oil changes every 3k miles etc, the basic maintenance stuff
maybe its just carbon buildup,cuase everything else looks okay but your plugs look a little clean, did you run e85 or gas in it?
subaru_gc8 is offline   Reply With Quote
Old 09-11-2020, 03:47 PM   #12
WRXXXED
Scooby Specialist
 
Member#: 432652
Join Date: Oct 2015
Location: Gap, PA
Vehicle:
2010 Subaru WRX STI
61K (Gray)

Default

Quote:
Originally Posted by subaru_gc8 View Post
maybe its just carbon buildup,cuase everything else looks okay but your plugs look a little clean, did you run e85 or gas in it?
Nothing but 93 ran through the car
WRXXXED is offline   Reply With Quote
Old 09-12-2020, 12:42 AM   #13
subaru_gc8
Scooby Specialist
 
Member#: 29292
Join Date: Nov 2002
Chapter/Region: SCIC
Location: Orange County CA
Vehicle:
2004 WRX wagon
silver

Default

Quote:
Originally Posted by WRXXXED View Post
Nothing but 93 ran through the car
yeah it could be just carbon build up.
subaru_gc8 is offline   Reply With Quote
Old 09-12-2020, 07:05 AM   #14
WRXXXED
Scooby Specialist
 
Member#: 432652
Join Date: Oct 2015
Location: Gap, PA
Vehicle:
2010 Subaru WRX STI
61K (Gray)

Default

Quote:
Originally Posted by subaru_gc8 View Post
yeah it could be just carbon build up.
Would the heads be okay to transfer after getting decked or should they be disassembled and cleaned?
WRXXXED is offline   Reply With Quote
Old 09-12-2020, 09:00 AM   #15
rtv900
Scooby Guru
 
Member#: 428511
Join Date: Aug 2015
Location: philadelphia
Vehicle:
2016 STI

Default

Quote:
Originally Posted by WRXXXED View Post
Would the heads be okay to transfer after getting decked or should they be disassembled and cleaned?
if they are straight and not in terrible condition they should be fine
nobody knows the condition
rtv900 is online now   Reply With Quote
Old 09-12-2020, 01:36 PM   #16
subaru_gc8
Scooby Specialist
 
Member#: 29292
Join Date: Nov 2002
Chapter/Region: SCIC
Location: Orange County CA
Vehicle:
2004 WRX wagon
silver

Default

Quote:
Originally Posted by WRXXXED View Post
Would the heads be okay to transfer after getting decked or should they be disassembled and cleaned?
that would be more of a question for your machinist,Its too hard ot tell from pics, if you are worried, get a straight edge on it and get a flashlight behind the straight edge and see if there is any light coming through... I know this isnt very sceintific or exact, but it will help put your mind at ease
subaru_gc8 is offline   Reply With Quote
Old 09-12-2020, 01:38 PM   #17
subaru_gc8
Scooby Specialist
 
Member#: 29292
Join Date: Nov 2002
Chapter/Region: SCIC
Location: Orange County CA
Vehicle:
2004 WRX wagon
silver

Default

Quote:
Originally Posted by WRXXXED View Post
Would the heads be okay to transfer after getting decked or should they be disassembled and cleaned?
that would be more of a question for your machinist,Its too hard ot tell from pics, if you are worried, get a straight edge on it and get a flashlight behind the straight edge and see if there is any light coming through... I know this isnt very sceintific or exact, but it will help put your mind at ease or you can paint the surface and get a long sanding block with some 1000 grit go across it and see how straight it is

I would rebuild the heads especially change the seals and the other wear items just for good measure personailly

Last edited by subaru_gc8; 09-12-2020 at 01:50 PM.
subaru_gc8 is offline   Reply With Quote
Old 09-12-2020, 07:49 PM   #18
Elbert Bass
Scooby Specialist
 
Member#: 283429
Join Date: May 2011
Chapter/Region: South East
Location: Down yonder.
Vehicle:
2016 Fuji Sunfire 03
Silver

Default

Nothing looks out of sorts - the plug may be wrong heat range or a lean mixture. All that carbon crap is normal. From the looks of those pistons I am guessing that engine is fairly new.
Funny thing - a head gasket coolant to combustion leak will actually steam the carbon off the head and pistons as a tell-tale of where the leak is. Looking at the pictures at the resolution posted I don't see signs of a leak for that head. Doesn't mean it doesn't, I'd need to inspect the gasket and look much closer at those mating surfaces for a proper diag. What were the results of your carbon dioxide test? If your bubbles were from the combustion chamber there would have been CO2. Check heads for warpage after cleaning.
Elbert Bass is offline   Reply With Quote
Old 09-12-2020, 09:55 PM   #19
WRXXXED
Scooby Specialist
 
Member#: 432652
Join Date: Oct 2015
Location: Gap, PA
Vehicle:
2010 Subaru WRX STI
61K (Gray)

Default

Quote:
Originally Posted by Elbert Bass View Post
Nothing looks out of sorts - the plug may be wrong heat range or a lean mixture. All that carbon crap is normal. From the looks of those pistons I am guessing that engine is fairly new.
Funny thing - a head gasket coolant to combustion leak will actually steam the carbon off the head and pistons as a tell-tale of where the leak is. Looking at the pictures at the resolution posted I don't see signs of a leak for that head. Doesn't mean it doesn't, I'd need to inspect the gasket and look much closer at those mating surfaces for a proper diag. What were the results of your carbon dioxide test? If your bubbles were from the combustion chamber there would have been CO2. Check heads for warpage after cleaning.
The engine is fairly new, about 60k miles i believe. I suspected that the engine gasses were getting into the coolant from the "boiling coolant" i saw when the upper coolamt reservoir was open and car was started and maybe some coolant into the cylinders but from what you say that sounds doubtful. Im not sure how to do a carbon dioxide test in coolant but the coolant was darker than usual and smelled of a petroleum product but no oil sitting on top or anything like that.

Im considering not getting the heads decked (for simplicity sake) and cleaning it up a bit and using a technique used by a few on here with success but ultimately making sure the heads are flat and not warped
WRXXXED is offline   Reply With Quote
Old 09-13-2020, 09:25 AM   #20
Elbert Bass
Scooby Specialist
 
Member#: 283429
Join Date: May 2011
Chapter/Region: South East
Location: Down yonder.
Vehicle:
2016 Fuji Sunfire 03
Silver

Default

Quote:
Originally Posted by WRXXXED View Post
The engine is fairly new, about 60k miles i believe. I suspected that the engine gasses were getting into the coolant from the "boiling coolant" i saw when the upper coolamt reservoir was open and car was started and maybe some coolant into the cylinders but from what you say that sounds doubtful. Im not sure how to do a carbon dioxide test in coolant but the coolant was darker than usual and smelled of a petroleum product but no oil sitting on top or anything like that.

Im considering not getting the heads decked (for simplicity sake) and cleaning it up a bit and using a technique used by a few on here with success but ultimately making sure the heads are flat and not warped
Is the car overheating at all? Are you constantly having to add coolant?
A small amount of bubbling when first started in the upper res is not that big a deal. given the look of the pics if you had a head gasket leak it probably be more likely to manifest after the engine warmed up and was put under load. As far as petroleum smell that is odd - if you had a head gasket leak and could smell it in the coolant (that would be a large noticeable leak with overheating, explosive overflow) it would smell more like exhaust.

CO2 test is when you draw air from the cooling system through a test fluid immediately after opening the pressure cap. The fluid will change color in the presence of CO2 which indicates combustion gas in the cooling system.

NOT resurfacing the heads or measuring for flatness is the worst thing to do if you tore it down for a suspected leak - the whole point of tearing it down is to find the cause. The majority of times the head surface isn't flat and that is the cause - especially with MLS gaskets.
You are allowed up to 0.05 mm (0.002") warpage, any more and you need to resurface. of the 300-400 suby engines I've repaired head gaskets on I've only seen 6 that didn't require resurfacing, and they were just within limits.

Here is a single stage tester and a two stage. I prefer the two stage in case you get a little coolant in the first stage. Mine is an old German made that I bought in 1986 working for VW. One of the most useful pieces of test gear I have besides my volt/ohm meter.

Elbert Bass is offline   Reply With Quote
Old 09-13-2020, 06:43 PM   #21
WRXXXED
Scooby Specialist
 
Member#: 432652
Join Date: Oct 2015
Location: Gap, PA
Vehicle:
2010 Subaru WRX STI
61K (Gray)

Default

Quote:
Originally Posted by Elbert Bass View Post
Is the car overheating at all? Are you constantly having to add coolant?
A small amount of bubbling when first started in the upper res is not that big a deal. given the look of the pics if you had a head gasket leak it probably be more likely to manifest after the engine warmed up and was put under load. As far as petroleum smell that is odd - if you had a head gasket leak and could smell it in the coolant (that would be a large noticeable leak with overheating, explosive overflow) it would smell more like exhaust.

CO2 test is when you draw air from the cooling system through a test fluid immediately after opening the pressure cap. The fluid will change color in the presence of CO2 which indicates combustion gas in the cooling system.

NOT resurfacing the heads or measuring for flatness is the worst thing to do if you tore it down for a suspected leak - the whole point of tearing it down is to find the cause. The majority of times the head surface isn't flat and that is the cause - especially with MLS gaskets.
You are allowed up to 0.05 mm (0.002") warpage, any more and you need to resurface. of the 300-400 suby engines I've repaired head gaskets on I've only seen 6 that didn't require resurfacing, and they were just within limits.

Here is a single stage tester and a two stage. I prefer the two stage in case you get a little coolant in the first stage. Mine is an old German made that I bought in 1986 working for VW. One of the most useful pieces of test gear I have besides my volt/ohm meter.

The car did not overheat at any point and i never had to add coolant. It was at more than 1/3 of a 5 gallon bucket but below the 1/2 way point. When i looked up the capacity it showed 8.1 quarts which is right for amount.


I will look at the flatness of the heads and see, it wasn't so much a smell of gas or oil but exhaust so there was definitely CO2 in the coolant.
WRXXXED is offline   Reply With Quote
Old 09-14-2020, 09:51 AM   #22
BlackFighter
Scooby Specialist
 
Member#: 193940
Join Date: Nov 2008
Location: Philly
Vehicle:
2004 WRX STI Black
RalliSpec Shortblock

Default

IMO that looks way more carbon build up for a 60k eng then there should be. Its caked on there and flaking off. Kinda does look like burn on sugar from coolant.
BlackFighter is online now   Reply With Quote
Old 09-14-2020, 11:22 AM   #23
WRXXXED
Scooby Specialist
 
Member#: 432652
Join Date: Oct 2015
Location: Gap, PA
Vehicle:
2010 Subaru WRX STI
61K (Gray)

Default

Quote:
Originally Posted by BlackFighter View Post
IMO that looks way more carbon build up for a 60k eng then there should be. Its caked on there and flaking off. Kinda does look like burn on sugar from coolant.
Hmmm, well i guess either way itll be coming apart. On my own stupid fault the car is speed density and i daily drove it with a turbo screen for the past year so it was sucking in road dust and im sure a lot of other things too... i just really liked the flutter

Bought a straight edge and will be checking for warpage this weekend, if all fairs well going to out the heads on the new shortblock and get it back in the car. If they are warped they will be decked and then put back together
WRXXXED is offline   Reply With Quote
Old 09-14-2020, 12:41 PM   #24
subaru_gc8
Scooby Specialist
 
Member#: 29292
Join Date: Nov 2002
Chapter/Region: SCIC
Location: Orange County CA
Vehicle:
2004 WRX wagon
silver

Default

Quote:
Originally Posted by BlackFighter View Post
IMO that looks way more carbon build up for a 60k eng then there should be. Its caked on there and flaking off. Kinda does look like burn on sugar from coolant.
yeah but it wasnt on the heads or on the spark plugs.
subaru_gc8 is offline   Reply With Quote
Old 09-14-2020, 01:43 PM   #25
BlackFighter
Scooby Specialist
 
Member#: 193940
Join Date: Nov 2008
Location: Philly
Vehicle:
2004 WRX STI Black
RalliSpec Shortblock

Default

Ya that's the weird thing. It almost looks like the heads and SB are from two different blocks
BlackFighter is online now   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

All times are GMT -4. The time now is 11:09 AM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2020 Axivo Inc.
Copyright ©1999 - 2019, North American Subaru Impreza Owners Club, Inc.

As an Amazon Associate I earn from qualifying purchases.